Actor Robert Downey Jr. trains with a coach on the set of Iron Man 2 in Los Angeles on Tuesday. The actor was sporting a pretty serious black eye on his left side, just weeks into shooting the sequel.

The big question is: Did he injure himself while training, or is it merely makeup for his character Tony Stark?

The first Iron Man was a critical smash and earned more than $100 million in its opening weekend last May, making it one of the year’s biggest surprise hits. The sequel takes place six months after Stark revealed his true identity as Iron Man, says director Jon Favreau. “How many superheroes are open about their true identities?” he asks. “We wanted to play with that idea. But it obviously has consequences — in his relationships, on the team. There are a lot of areas we can explore.”